Field
The present disclosure relates to grapple apparatus and more particularly pertains to a new dual action grapple apparatus providing substantially sequential movement of portions of the grapple arm for more effective grasping of objects.
Description of the Prior Art
In the design of grapple apparatus for buckets or other implements, it is generally desirable to maximize three characteristics. The first characteristic is to achieve a relatively small closing gap between the tips of the grapple teeth and the bucket when the grapple is in the closed position to help hold the grasped contents in the bucket. The second characteristic is to achieve a relatively large opening when the grapple is in the open condition to permit the grapple to grasp large objects or handle large amounts of material. The third characteristic is to achieve minimal “overhang” of the grapple when the grapple is in the open position, which is the distance that the tips of the grapple teeth are forward of the bucket when the bucket is flat on the ground surface. More specifically, relatively minimal overhang means that the grapple vehicle operator can drive up to tall piles of material (such as bunkers of silage) and begin to manipulate the material with the edge of the bucket before the open grapple interferes (by contact) with the material.
However, known grapple designs tend to have to compromise on one or more of these three basic characteristics to maximize the remaining characteristic(s), and usually focus on minimizing the closing gap. The typical grapple with a single cylinder rotating the grapple simply can't do well at all three characteristics with a bucket of typical size.
For example, the design shown in FIGS. 17A and 17B is highly popular because it has a minimal closing gap and moderate degree of opening distance in the open position, but it also suffers from excessive overhang when in the open position. As another example, the design shown in FIGS. 17C and 17D has a relatively wide opening in the open condition with only moderate overhang, but the closing gap is large.
U.S. Pat. No. 8,615,907 presents one approach to maximizing these three characteristics and uses a mechanical “lock” provided by a guide arm, and works well in many situations. However, there are situations where a particularly large object or a sufficiently large amount of material will prevent the grapple from rotating from the open positon toward the closed position (see FIG. 18). If the guide pin is still engaged with the guide arm when the grapple contacts the large object, the pivot link can't rotate to the closed position and this may result in a severe bending stress on the guide arm and a severe side load on the cylinder rod. Another drawback of the mechanical lock system of U.S. Pat. No. 8,615,907 is mechanical wear. The guide arm and guide pin contact and rub every time the grapple opens and closes. These elements are both wear parts and need to be periodically replaced. Finally, the mechanical lock system cannot be effectively scaled up to work with a large grapple, as the size of the guide arm would be highly impractical.